Coal cutting bit having a skewed cutting face



March 26, 1957 H. M. MORROW 2,786,664

com. CUTTING BIT HAVING A SKEWED CUTTING FACE Filed June 24, 1955 Fig. 3

INVENTOR. HARRY M. MORROW United States atent O COAL CUTTINGBIT HAVING A SKEWED CUTTINGFACE H y Mo w-Navar 1 1 a si t Th y Bowdil .Camp ny Application June 24, '1955, Serial' No.- 517,797 8 1 26 -3 The invention relates in general to cutting bits and more particularly tobits having skew faces for cutting coal or other substances.

In the mining of coalor other substances, a cleft is cut in the lower level of the vein by means of a cutter bar around which revolves a power driven endless chain carrying a plurality of staggeredly arranged cutting bits constituting the subject matter of this invention. Each of the staggeredly arranged cutting bits is therefore .adapted to travelin itsown continuous cutting path. it might be said that this euttingpath lies substantially in a first plane. .Theshelf formed by the cleft is subsequently'broken ofiby means of explosives or other suitbl methods W eneutt s theclert in the in e e o ec nomya e s ving f p we iis. hig y des rabl tha th su t ng its b no only str ng n .durablebu Anobject of theinvention is to provide .a. cutting bit ha in a i h cutting eifi isncr An he ie e th nv nt omi to Provide a coa cutting bit whichhas .aleadingedge and .a.trailing edge which leadingedge will precede thetrailingedgein engagingeoal to he cut wherebythe total forced-rivingthe coalcuttingbit ,will be tr.ansmitted;through the cutting bit to,a smaller unit area thanin ordinary cutting bits thereby producing. a. higher. cutting force. per. unitv area.

Another object of the invention iszthe provisionof a cutting hitvvhich. requires a minimum of power tov operate.

Another objectof the invention is to provide a. cutting bithaving aleading edge and atrailing. edgewhereby the le ing. dg i p ecede thata ing e i e ga ing material'tobe cut.

iAnothe-r. object. of. the invention vis to providea cutting bit with first'and second- .side walls and a cuttingiace which lies ina plane-other than 21 planewhich isnormal to .a longitudinal reference plane which extends ,intermediate the 1 first and second; Side walls Another object of theinvention is-to providea coal outtingbit-Whiehis adapted'totravel in a continuous cutting pathtocut coal with a cutting face whichis skewed I with respect to thecutting path thereby causing one edge ofthecutting'bitto engagecoal toi-be cut before the other. edge-engagesthe coal.

Another object of the invention is-to provide a doubleended coal cutting bit adapted to 'be carried ina bit holder havingfirst and second opposed faces which haveegual but opposite slopes whereby the bit may be held in the h l rby ei hererr Other objects anda iiullerunderstanding of the i nvention maybehad by referring to the following description and claims taken incombination .with the accom- P nn ng. drawings swhic Figure 1.-is aside elevationalview of -the cutting bit of this invention. I

Figure 2.is a .view.of:the-cutting-bit taken in adirection which is normal'to theplane in which the cutting 2,786,664 Patented .Mar. 26, 1 9 57 "ice 2 -face of'the cutting resides and therefore shows the tr ue configuration of the cutting face.

Figure 3 is a cross sectional view oftheeuttirrglbit taken alongthe line 3-3 of Figure 1.

Figure 4 is a cross sectional view of the cuttingbit taken alongthe'line 44 of'Figure' 1. i I

' Figure 5 is a cross sectional view of ,the-clittiiigjhit taken along the line -'5,5 offigure '1 "F gu 'i a end vi p t e cu tiagrbittak e aldag the lines 6--6 ofjFi gure 1. I

Wit re en t i'F gures 1 thr agh-fi o t sempa 'y g d ing do ble nded .coa cutt g .b l5 i shown w i i mpr es solid piece o m t l .whiq tmay e. mad o har ened. st 1... o er. t withs an he-s e e cu tin icn at on t wh hit issubiected. The: soli piece of rnetal as best seen in Figures 1 ,and 2-has first and second generally rhomboidal side wall means .17 and 18 respectively and a-thickened central-body portion 19 whichnarrows, down to first v and secondend pon tions .22 and 23 respectively which are narrower than the centralbody. portion 19. Thedoubleendedbit has first and second leading edges 2.0 and .2t1.,andfir.st and second trailing edges 25 and 16. It wilhbe notedtthat these sidewall means are not exaetlyrhomboidal in, shape sincethe leadingedges 2 0 and .21 which make up-two Sides of the first .rhomboidallside wallmeans- 17 curve s h l a y m eachether anisinc h zail na ed es 25 and, 26',whi c h make uptwo sides ofthe second hornboidal side .wall .means .18 c-urve slightly toward- 'eaeh other as seen in Figure l. The first-leading edgeflil and the first trailing edge 25. define a first; skew cutting face 2S which terminates-in a first cuttingpoint or end 3.0; .The skew cuttingface 28 .has a first and- .sec ond side surface portion,;29 and .351 r espec.t-ivel-y. T115566;- nd l a n ed 21 th n t a as e 12 d:- fine aseeond skew cutting face 32 ,w 'h-ich-terminates in asecond cutting point or end 3 3. ,It n1ay"be;said hat the firsthand secondcuttingpoints. 3!) an 33;are located at h i m t ic l oppo ha p an es tth tsem erally rhomboidal side wall -rnea-ns. As best seen gin Figure-tithe; first and secondcutti'ngfaces 28.21.1151 3. are non-P le n as b s n". i-gu1?e 1 thes .ell t-in' facesare offset relative to ,each other. .The tiirst-general'ly rhomboijdalside wall- 1nea ns 17 extends between and connects the'first and second. leading edges 2.0 {and 21. andthe second generally rhomboidalside-wall-means 18 extends between and connects -:the-fi'rst and :second trailingedges 25 an d'26. Thedistance indicated byz the reference numeral 35 between .the leadi'ngedges '20 and 21 esrneasured at the thickened centralibodyportion 19 along the .fi'rst rhomb0idal side wall -means 17 is greater than the distance 36 between-the trailing edges 25 and 26 .as measured at the thickened central body portiongl9- along the second rho-mboidal sidewall means 18. The first and second rhomboidal sidewall means 17 and 18 and the first cutting face" 28 converge at-the first cutting pointorend portion to define thiscutting point andthe firstand second side wallmeans 17 and Sand-the second. cutting face33 converge at thesecond cutting point or endportion 33. The'first and second-side wall means are connected together andmeet at opposed ends of the rhomboidal configurationin first andsecond connecting edge portions '38 and 39 respectively; The distances 35 and 36 if measured along the connecting edge portions 38 and 3?, instead of along the first and second side wall means 17 .and 18, will be substantially equal;

A plane extending through the first connecting edge portion 38-.andthrough the'second connecting edge p'ortion-539 Wouldrbesubstantiallyintermediatethe first and second ;.rhombo idal side :wall means '17 and 18'. KT-hie 3 plane is indicated in Figures 1, 3, 4, and 6 by the dotdash lines 42 and constitutes a longitudinal reference plane. The cutting bits of this invention are removably mounted in the lugs of the endless power driven chain which revolves around the cutter bar. The holder for holding the bits of this invention might be similar to the holder which is shown in Patent No. 2,255,856 issued to H. M. Morrow on September 16, 1941 except that the surface which the skew cutting faces are to rest on while being held would have to be skewed in the same manner. When one of the cutting points of the bit wears away the bit is reversed within the same holder thus giving a double cutting life to the bits. The bits are held on the chain lugs at a slight forward angle as shown in Figure l and approach material to be cut generally in a direction indicated by the arrow 43 in Figures 1 and 6. As best seen in Figures 3, 4 and 5 the cutting bit of Figure 1 is of the type which has concave sides which provides a greater cutting clearance as the bit wears away. This type of bit is shown more completely in Patent No. 2,217,347 issued to H. M. Morrow on October 8, 1940. As best seen in Figure 6 the cutting face 28 lies in a plane 44 and the cutting face 32 lies in a plane 45. As seen in this View the cutting faces 28 and 32 lie in planes which are non-parallel and which are different from any plane which is normal or perpendicular to the reference plane 42. Because the cutting faces are other than normal to the reference plane 42 the cutting faces are skewed with respect to the reference plane and are also skewed with respect to the direction of travel of the cutting bit when mounted in the lugs of the endless power driven chain. As a result of this skew cutting face the leading edge 20 will precede the trailing edge 25 in engaging coal or other material to be cut. This means that the leading edge 20 will also normally precede any other portion of the cutting face in engaging material to be cut. As a result the total power which is driving the cutting bit in its cutting path will be transmitted to a smaller unit cutting area which in turn will mean that the cutting force per unit area will be greatly increased. These factors contribute to the fact that less power is required to drive this type of bit in a cutting orbit through coal or similar material and that greater etficiency of operation results.

The cutting tip portion of the coal cutting bit 15 of this invention taken from approximately the position where line 4-4 intersects the bit in Figure 1 to the cutting point 30 may be referred to as a configuration which is substantially that of a pyramid. The cutting point 30 would constitute the apex of the pyramid and Figure 4 would constitute the shape of a cross section of the pyramid. This cross section is generally triangular in shape with the first and second side wall means 17 and 18 respectively making up two sides of the triangular shape and the first skew cutting face 28 making up another side of the triangular shape.

The skew cutting face of this invention may also be applied to other types of coal cutting hits such as those shown in Patent Numbers 1,435,309; 1,902,420; 2,039,747; 2,131,188; 2,156,726; 2,168,794; 2,263,590.

Although this invention has been described in its pre ferred form with a certain degree of particularity, it is understood that the 'pres-ent disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

l. A double-ended bit comprising a solid piece of metal having a thickened central body portion and narrowed first and second end portions, said piece of metal having first and second generally rhomboidal side wall means, first and second leading edges, and first and second trailing edges, said first leading and trailing'edges defining a first skew cutting face terminating in a first cutting point, said second leading and trailing edges defining a second skew cutting face terminating in a second cutting point, said first and second faces having generally diamond shaped configurations, said first generally rhomboidal side wall means extending between said first and second leading edges and said second generally rhomboidal side wall means extending between said first and second trailing edges, the distance between said leading edges at said thickened central body portion measured along said first rhomboidal side wall means being greater than the dist-ance between said trailing edges at said thickened central body port-ion measured along said second rhomboidal side wall means, said first and second side wall means meeting at first and second connecting edge portions respectively said first and second rhomboidal side wall means and said first cutting face converging at said first cutting point and said first and second side wall means and said second cutting face converging at said second cutting point, a plane extending through said first and second connecting edge portions and substantially intermediate said first and second generally rhomboidal side wall means constituting a longitudinal reference plane, each said first and second cutting face lying in a plane different from a plane which is normal to said reference plane.

2. A double-ended bit comprising a piece of metal having first and second substantially rhomboidal side wall means, first and second leading edges, and first and second trailing edges, said firstleading and trailing edges defining a first skew cutting face terminating in a first cutting end portion, said second leading and trailing edges defining a second skew cutting face terminating in a second cutting end portion, said first substantially rhomboidal side wall means extending between said first and second leading edges and said second substantially rhomboidal side wall means extending between said first and second trailing edges, the distance between said leading edges along said first rhomboidal side wall means being greater than the distance between said trailing edges along said second rhomboidal side wall means, said first and second rhomboidal side wall means and said first cutting face converging at said first cutting end portion and said first and second side wall means and said second cutting face converging at said second cutting end portion, a plane extending substantially intermediate said first and second substantially rhomboidal side wall means constituting a longitudinal reference plane, each said first and second cutting face lying in non-parallel planes which non-parallel planes are other than normal to said reference plane.

3. A double-ended bit comprising a solid piece of metal having first and second substantially rhomboidal side wall means, first and second leading edges, and first and second trailing edges, said first leading and trailing edges defining a first skew cutting face terminating in a first cutting point, said second leading and trailing edges defining a second skew cutting face terminating in a second cutting point, said first substantially rhomboidal side wall means extending between said first and second leading edges and said second substantially rhomboidal side wall means extending between said first and second trailing edges the distance between said leading edges along said first rhomboidal side wall means being greater than the distance between said trailing edges along said second rhomboidal side wall means, said first and second rhomboidal side wall means and said first cutting face converging at said first cutting point and said first and second side wall means and said second cutting face converging at said second cutting point, a plane extending substantially intermediate said first and second substantially rhomboidal sidewall means constituting a longitudinal reference plane, each said first and second cutting face lying in a plane different from a plane which is nor mal to said reference plane.

4. A double-ended bit comprising a solid piece of metal having first and seCOtld side wall means,-first and second leading edges, and first and second trailing edges, said first leading and trailing edges defining a first cutting face terminating in a first cutting end portion, said second leading and trailing edges defining a second cutting face terminating in a second cutting end portion, said first side wall means extending between said first and second leading edges and said second side wall means extending between said first and second trailing edges, the distance between said leading edges along said first side wall means being greater than the distance between said trailing edges along said second side wall means, said first and second side wall means and said first cutting face converging at said first cutting end portion and said first and second side wall means and said second cutting face converging at said second cutting end portion, a plane extending substantially intermediate said first and second side wall means constituting a longitudinal reference plane, each said first and second cutting face lying in a plane different from a plane which is normal to said reference plane.

5. A double-ended bit comprising a piece of metal having first and second side wall means, first and second leading edges, and first and second trailing edges, said first leading and trailing edges defining the sides of a first cutting face, said second leading and trailing edges defining the sides of a second cutting face, said first side wall means extending between said first and second leading edges and said second side wall means extending between said first and second trailing edges, a plane extending substantially intermediate said first and second side wall means constituting a longitudinal reference plane, each said first and second cutting face lying in planes dilferent from planes which are normal to said reference plane.

6. A coal cutting bit having a cutting tip portion defined by first and second side wall means and a cutting face, said first and second side wall means and said cutting face forming substantially a pyramid terminating in an apex, said pyramid having a generally triangular shaped cross section at a spaced distance from said apex,

said first and second side wall means meeting at a connecting edge portion, said connecting edge portion lying in a reference plane which extends intermediate said first and second side wall means, said cutting face lying in a plane other than a plane which is normal to said reference plane.

7. A coal cutting bit adapted to travel in a continuous cutting path including a skew cutting face and first and second side wall means, said skew cutting face terminating in a cutting point, said cutting face having first and second side surface portions, said first side wall means meeting said first side surface portion thereby defining a leading edge and said second side wall means meeting said second side surface portion thereby defining a trailing edge, said first and second side wall means and said skew cutting face converging at said cutting point, said first and second side wall means meeting at a connecting edge portion, said connecting edge portion lying in a reference plane which extends intermediate said first and second side wall means, said skew cutting face lying in a plane different from a plane which is normal to said reference plane, said leading edge of said coal cutting bit being in advance of said trailing edge when said bit travels in said continuous cutting path thereby preceding said trailing edge in engaging coal to be cut.

8. A coal cutting bit including a cutting face and first and second side wall means, said cutting face terminating in an end portion, said first side wall means meeting said cutting face thereby defining a leading edge and said second side wall means meeting said cutting face thereby defining a trailing edge, said first and second side wall means and said cutting face meeting at said end portion, a plane extending intermediate said first and second side wall means constituting a reference plane, said cutting face lying in a plane different from a plane which is normal to said reference plane.

References Cited in the file of this patent UNITED STATES PATENTS 2,657,916 Von Stroh Nov. 3, 1953 

